Gracefully handle lack of network connection.

lib/spack/spack/error.py

@@ -11,3 +11,10 @@ class UnsupportedPlatformError(SpackError):
     """Raised by packages when a platform is not supported"""
     def __init__(self, message):
         super(UnsupportedPlatformError, self).__init__(message)
+
+
+class NoNetworkConnectionError(SpackError):
+    """Raised when an operation needs an internet connection."""
+    def __init__(self, message, url):
+        super(NoNetworkConnectionError, self).__init__(message)
+        self.url = url

lib/spack/spack/package.py

@@ -664,21 +664,27 @@ def fetch_available_versions(self):
             url_regex = os.path.basename(url.wildcard_version(self.url))
             wildcard = self.version.wildcard()
 
-            page_map = get_pages(self.list_url, depth=self.list_depth)
-            for site, page in page_map.iteritems():
-                strings = re.findall(url_regex, page)
+            try:
+                page_map = get_pages(self.list_url, depth=self.list_depth)
 
-                for s in strings:
-                    match = re.search(wildcard, s)
-                    if match:
-                        v = match.group(0)
-                        self._available_versions.add(Version(v))
+                for site, page in page_map.iteritems():
+                    strings = re.findall(url_regex, page)
 
-            if not self._available_versions:
-                tty.warn("Found no versions for %s" % self.name,
-                         "Check the list_url and list_depth attribute on the "
-                         + self.name + " package.",
-                         "Use them to tell Spack where to look for versions.")
+                    for s in strings:
+                        match = re.search(wildcard, s)
+                        if match:
+                            v = match.group(0)
+                            self._available_versions.add(Version(v))
+
+                if not self._available_versions:
+                    tty.warn("Found no versions for %s" % self.name,
+                             "Check the list_url and list_depth attribute on the "
+                             + self.name + " package.",
+                             "Use them to tell Spack where to look for versions.")
+
+            except spack.error.NoNetworkConnectionError, e:
+                tty.die("Package.fetch_available_versions couldn't connect to:",
+                        e.url, e.message)
 
         return self._available_versions
 

lib/spack/spack/util/web.py

@@ -6,6 +6,7 @@
 from HTMLParser import HTMLParser
 
 import spack
+import spack.error
 import spack.tty as tty
 from spack.util.compression import ALLOWED_ARCHIVE_TYPES
 
@@ -90,12 +91,10 @@ def _spider(args):
                 for d in dicts:
                     pages.update(d)
 
-    except urllib2.HTTPError, e:
+    except urllib2.URLError, e:
         # Only report it if it's the root page.  We ignore errors when spidering.
         if depth == 1:
-            tty.warn("Could not connect to %s" % url, e.reason,
-                     "Package.available_versions requires an internet connection.",
-                     "Version list may be incomplete.")
+            raise spack.error.NoNetworkConnectionError(e.reason, url)
 
     return pages